Kharibegashvili, S. S., and B. G. Midodashvili. “Boundary-Value Problem for a Class of Nonlinear Systems of Partial Differential Equations of Higher Orders”. Ukrains’kyi Matematychnyi Zhurnal 74, no. 6 (July 8, 2022): 856 - 868. Accessed August 15, 2022. https://umj.imath.kiev.ua/index.php/umj/article/view/6968.